Heretofore, many kinds of buckles for fastening or retaining a belt, or the like, have been made and used. These conventional buckles have various structures and many functions in accordance with their intended purposes of use.
However, with respect to this general type of buckle, if the structure thereof is such as to assuredly maintain the fastening or retaining state in order to increase the fastening or retaining capability of the belt or the like, it often becomes complicated or bothersome to insert or withdraw the belt or the like into or from the buckle. Moreover, the structure thereof often becomes complicated and bulky. On the other hand, if the buckles are so constructed as to enable easier insertion or withdrawal of the belt or the like therein or therefrom, the retaining state of the buckle is often difficult to maintain and the belt or the like is often unexpectedly withdrawn or loosened.
It is thus difficult to fulfill all of the requisites at the same time, since some of them are incompatible with the others. Unless good balancing of the incompatible factors can be achieved, other improvements in the structure of the buckles is meaningless.
As a typical example of a means for retaining a belt which attempts to fulfill all of the above requisites to the utmost possibility, there is known a buckle such as shown in FIGS. 7 through 9, in which the structure is simplified so as to secure the belt by means of a retaining cam piece of a stopper piece so that the belt can be more easily inserted and released and yet the belt can be tightly fastened by means of the cam piece. More specifically, this conventional buckle comprises a bottom wall 101, side walls 102 provided upon opposite sides of the bottom wall 101, a stopper piece 103 interposed between the side walls 102 and supported at both sides of one end thereof by pivotal supporting means 104, and a cam piece 105 disposed in such a manner as to be generally perpendicular to the stopper piece 103 within the vicinity of the pivotal supporting means 104, whereby a belt inserted between the stopper piece 103 and the bottom wall 101 is frictionally engaged with the bottom wall 101 by means of a top portion 105a of the cam piece 105.
This conventional buckle is simple in structure and easy to handle. On the other hand, it has a shortcoming in that since the belt is fastened merely by being biased into contact with the bottom wall 101 by means of tip portion 105a of the cam piece 105, even when the belt 106 is pulled back in the F.sub.1 direction as seen in FIG. 8, the biasing of frictional pressure of the tip portion 105a of the cam piece 105 is not increased. Thus prevention of withdrawal of the inserted belt is not in fact guaranteed.
Furthermore, in this type of conventional buckle, the cam piece 105 has to have sufficient length from the pivotal supporting position of the stopper piece 103 in order to attain a sufficient biasing or frictional pressure for the cam piece tip portion 105a. As a result, the buckle is required to have a substantial thickness denoted by d in FIG. 9. Moreover, since the cam piece 105 is required to be pivoted from a horizontal position to a vertical position perpendicular to the bottom wall 101 as shown by the phantom lines of FIG. 9, a large operating space denoted by s is required for the stopper piece 103 as is also shown in FIG. 9.
Furthermore, the buckle is required to be tightly held with one's fingers when the belt 106 is tightly fastened. Therefore, in order to pivotally move the stopper piece 103 immediately after the belt is tightly fastened, the hand holding the belt 106 or the buckle is required to be removed therefrom so that the hand can be engaged in the pivotal movement of the stopper piece 103. Thus, the operation is bothersome. In addition, the belt once fastened is likely to loosen.
As another example of the prior art, there is known another conventional buckle which is shown in FIGS. 10 through 12.
This conventional buckle comprises a main body 202 connected with a belt 201, a stopper member 203 detachably fitted within the main body 202, and a winding rod 204 provided within the buckle main body 202, another belt 205 (or the opposite end of the same belt) wound around the winding rod 204 being urged against one side of the rod 204 by means of the a lower sidewall portion of the stopper member 203.
As a result, when the belt 205 is tightly pulled in the F.sub.1 direction and the stopper member 203 is pushed downwardly into the main body 202, the stopper member 203 presses the belt 205 against the winding rod 204 so as to retain it in the tightened state. When the tension of the belt 205 is released in that state, the belt 205 is pulled back in the F.sub.2 direction as shown in FIG. 11. As a result, the stopper member 203 tends to be pulled further into the main body 202 as shown by the arrow extending in the F.sub.3 direction. As a result, the stronger the reaction of the belt 205 is, the firmer is the retaining state that the stopper 203 creates. This is one of the advantages of this conventional buckle.
Another advantage of this conventional buckle is that the belt 205 can be comparatively easily and smoothly released by raising the stopper member 203 or pulling up the stopper member 203 in the F.sub.4 direction.
However, in this conventional buckle, the stopper member 203 must be raised each time the belt 205 is to be released. Moreover, the stopper member 203 must be continuously held in its raised stated until the belt 205 is withdrawn to a predetermined extent. This makes release of the belt bothersome. In addition, the stopper member 203 must be held in its raised state, since otherwise it would fall again due to contact resistance with the belt 205, thus resulting in an unexpected interruption of withdrawal of the belt.